Please, what should I do?

Anonymous
I once smiled at this guy (distant friend) and ever since, he'd try locking eyes with mine. Once, I was talking to someone and I noted him staring from afar from the corner of my eye. I ignored this and walked over to some other place, but he continued staring. I moved again and he leaned over to still continue staring. At this point, it turned into watching as his eyes followed everywhere I walked. I even hid behind something hoping he'd stop. However, when I stepped out, he was still there.. with the same look, still staring directly at me (like he was waiting until I came out of my hiding spot to stare). I mean I've been stared at by guys before and I take it lightly, but this wasn't staring, it was watching. It felt like sexual harassment and it was intimidating- I couldn't stop crying when I went home. I'm 25f, he's 28m.
Updates
+1 y
by the way he was already a distant friend of family, he was 'normal' before and only started doing this after I smiled at him at an event.
Please, what should I do?
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